OP0199 HAND OSTEOARTHRITIS PHENOTYPES AND THEIR ASSOCIATIONS WITH PAIN AND CHANGE IN PAIN
Authors: E. Mulrooney, T. Neogi, H. Solveig Dagfinrud, H. B. Hammer, P. Steen Pettersen, T. K. Kvien, K. Magnusson, I. K. Haugen
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Hand osteoarthritis (OA) pain is characterized as heterogeneous and multifactorial. Different pain patterns may be explained by underlying phenotypes, which previously have not been explored. <h3>Objectives</h3> Using the biopsychosocial framework, we aimed to identify possible hand OA phenotypes and explore the associations with pain intensity and change in pain during a four-year follow-up. <h3>Methods</h3> Latent class analysis was used to determine classes of people with hand OA, based on baseline examination (2016-17), followed by posterior fit statistics. Biological, psychological, and social domains were examined by self-reported questionnaires, clinical assessment and imaging. Central pain sensitization was tested by pressure pain thresholds (PPT; kg/cm<sup>2</sup>) and temporal summation (TS). Pain intensity at baseline and follow-up (2019-21) was self-reported on a Numeric Rating Scale (0-10) for hand and overall bodily pain the last 24 hours. Change in pain was calculated for both pain measures. Differences of the biopsychosocial variables and pain measures were assessed by one-way ANOVAs and chi-squared tests. The relations of the classes to the pain outcomes were analysed by linear regression. <h3>Results</h3> We identified five classes (Table 1). The highest pain intensity was reported by the class with low OA severity but higher burden of the other factors (Class 5), whilst the class with the most OA severity of the hands and lower extremities (Class 4) reported approximately one point less for pain intensity (Figure 1). Classes showed little change in pain and there was no significant difference (data not shown). Significant differences were found across all classes in association to baseline and follow-up pain. However, not for change in pain (data not shown), except Class 5 and change in hand pain (beta (95% CI); 1.13 (0.02, 2.25)). Class 5 indicated the most hand and overall bodily pain in comparison to the reference group (Class 1) with a beta (95% CI) of 3.27 (2.32, 4.22) and 3.08 (2.10, 4.07) at baseline and 2.04 (1.02, 3.06) and 2.74 (1.73, 3.76) at follow-up, respectively. The difference was smaller when comparing for Class 4 to the reference group with a beta (95% CI) of 2.15 (1.27, 3.02) and 2.20 (1.27, 3.13) for hand pain and overall bodily pain at baseline, and a beta (95% CI) of 1.38 (0.46, 2.31) and 1.66 (0.74, 2.58) at follow-up. Class 3 indicated similar baseline values as Class 4 (Hand and overall bodily pain: beta (95%) of 2.24 (1.51, 2.97) and 1.89 (1.12, 2.65)). <h3>Conclusion</h3> We identified five potential hand OA phenotypes which associated with pain intensity at baseline and four years later. The phenotype with low OA severity, but more pain sensitization, comorbidities, higher psychological and social burden reported more pain than the phenotype with the most severe OA in the hands and lower extremities, reflecting the discordance between OA severity and pain experience. <h3>Acknowledgements</h3> The authors would like to thank the all the study participants, the project coordinator Janicke Magnus and the user representative, Thalita Blanck, in addition to the research assistants and physicians who contributed in the Nor-Hand study. <h3>Disclosure of Interests</h3> Elisabeth Mulrooney: None declared, Tuhina Neogi: None declared, Hanne Solveig Dagfinrud: None declared, Hilde Berner Hammer Speakers bureau: AbbVie, Novartis, Lilly, UCB; Honoraria for lectures, Consultant of: AbbVie, Novartis; Advisory Board, Pernille Steen Pettersen: None declared, Tore K. Kvien Speakers bureau: Amgen, Celltrion, Egis, Evapharma, Ewopharma, Hikma, Oktal, Sandoz, Sanofi; Honorarium mee for lectures , Consultant of: Amgen, Celltrion, Biogen, Eli Lilly, Gilead, Mylan, Novartis, Pfizer, Sandoz, Sanofi. AbbVie: Advisory board , Grant/research support from: AbbVie, BMS, Pfizer, Novartis, UCB; Payment to institution , Karin Magnusson: None declared, Ida K. Haugen Speakers bureau: Novartis, GSK; Honorarium for lecture, outside of the submitted work, Grant/research support from: Pfizer/Lily (ADVANCE); Paid to institution.